The source said the prosecutor's written request, which may or may not be accepted by the judge, said UBS had to answer to claims it had ``cheated'' French clients by sponsoring a Luxembourg-registered fund, Luxalpha, which for years fed assets directly to Madoff without saying so in the prospectus.

These claims also form part of an ongoing U.S. lawsuit against UBS pursued by Irving Picard, the trustee seeking money for victims of the Madoff fraud. The bank has always denied the allegations.

Madoff was arrested in December 2008 and pleaded guilty three months later to running a giant Ponzi scheme. The 74-year-old is serving a 150-year sentence in a North Carolina federal prison.